[quote author=“mckenzievmd” date=“1192672931] but something identical in evry conceivable way IS the thing it duplicates in all ways that matter, even if it has come to be such by a different mechanism.

Yes Brennen but what casts doubt in my mind is a question I asked much earlier on the thread and I don’t think you had a go at.

If there happens to be a malfunction and you survive on Earth but never the less you appear on Europa.

How would you feel if the operators said all is well you’ve arrived so we will destroy you now?

I think I’d be horrified by the idea. But I’m sure that isn’t because of the minute I missed on Europa or the fact that the copy will be very, very slightly different.

So if it isn’t, am I just being irrational about this? Or is there something else?

I would say that the twin on Europa IS you, at least at the precise moment of duplication. There are two of you. Then at the moment they begin to have different experiences, they begin to be different, though not nearly as much as any two other individuals.

Stephan,
I think the surviving twin on Earth would be you for a moment, then gradually you would become different from each other (though not much). And because they are both you, of course they both have the same desire and claim of a right to life. This stays true even as you begin to be different from each other. What is irrational is if all your friends or your wife decided they wanted to keep one of you and destroy the other, even if there was no detectable difference between the two copies. It is assigning value on the basis of the history of how the thing came to be, rather than on the basis of characteristics of relevance inherent in the person/object, that I consider irrational. And at the moment of creation, you would even have the same history up to that point, so it makes no sense to value the two copies of you differently.

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I think the surviving twin on Earth would be you for a moment, then gradually you would become different from each other (though not much). And because they are both you, of course they both have the same desire and claim of a right to life. This stays true even as you begin to be different from each other. What is irrational is if all your friends or your wife decided they wanted to keep one of you and destroy the other, even if there was no detectable difference between the two copies. It is assigning value on the basis of the history of how the thing came to be, rather than on the basis of characteristics of relevance inherent in the person/object, that I consider irrational. And at the moment of creation, you would even have the same history up to that point, so it makes no sense to value the two copies of you differently.

I don’t believe there can be anything rational about value, I think value depends on emotion, without emotion there is no value but that is a whole other subject.

Anyway back to the plot, you suddenly feel like you would be killed because of this minutes difference. You have a desire for life where as before you were content to be destroyed

Yes there is a slight technical difference but it shouldn’t be a big deal should it?

I would say that the twin on Europa IS you, at least at the precise moment of duplication. There are two of you. Then at the moment they begin to have different experiences, they begin to be different, though not nearly as much as any two other individuals.

Sorry, I was less than clear. “Twin-Earth” is a separate thought-experiment that I brought up in this thread. It’s the idea that there could be another planet around another star in some far-off galaxy that was exactly identical to our Earth. There would be a twin-Brennen on that planet, answering twin-Doug.

But he wouldn’t be you.

And further, imagine some evil alien who came down to you and said he was going to kill you (or blow up Earth), and leave twin-you (or Twin-Earth) alone. Now, clearly he’s guilty of murder, even mass murder. Clearly it’s of no interest to YOU, Earth-Brennen, that there happens to be or not to be some identical twin somewhere. He’s a different guy.

I guess then it comes down, again, to semantics, and what you mean by identity. I would say if we are identical in every way and in every experience up to the moment of destruction, then Twin-Brennen is me. There are then two of me. When their experiences diverge (because the alien threatens to kill one of me) then they become different because they are no longer identical. But the issue of whether I would feel ok being killed if another me existed is a different issue. 1000 copies of me could exist, all identical in all properties, and I would argue they are all me. Each has a desire to live, and if one is threatened and all the others aren’t then that one may still want to live, but it is no longer identical to the others because its experience has diverged from their.

This is different from the teleportation question in that I can comfortably volunteer to be destroyed knowing I will be recreated identical in all ways internally and externally because I know that I won’t notice a difference. If I am killed and the other me isn’t, that’s a difference I’d notice. So I would still say identity of properties is what defines two things as identical. But if the two things are physically separate and having even that slightly different experience, then their properties are no longer iden tical so they aren’t the same thing. In that sense, you can never really be duplicated because standing a foot apart from each other makes a detectable difference in properties (retinal and brain activity, other sensory activity, etc). However small this difference the two things are then no longer truly identical in all respects.

Whew, for a pointless exercise this sure takes a lot of mental energy!

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So if you learned that there was a Twin-Earth and that Twin-Brennen would go on living his life, you wouldn’t mind being killed? I find that quite a surprising claim, one that is not particularly credible. I can see that you are forced into that position by your considered take on what personal identity amounts to, but I don’t believe you really think that way, or would act that way if it came down to it. And then the question is whether you really believe this, or simply talk that way for the purposes of an exercise you view as pointless. Of course, if the exercise were really pointless, there would be no particular importance to getting accurate about it.

And to repeat, it is not true that “identity of properties is what defines two things as identical.” Again, you and twin-you are not identical, but have identical properties. Similarly, it is probably true that each electron, neutron, proton, photon is property-identical, yet they are numerically distinct.

You may well say that it doesn’t matter if the Mona Lisa is replaced by a copy, but it is simply false to say that the Mona Lisa hasn’t been replaced when it has.

... or to say that what is on the wall isn’t a copy when it is.

One thing is whether we can tell if X, Y, or Z is true, and another is whether X, Y or Z is in fact true.

What I’m saying is that twin-earth Brennen and I are essentially the same person in all ways that matter if we have exactly the same properties, including those that are the result of experience. I don’t see logically how we could have identical properties and not be identical. If they are not detectably different but really are different in some way, then that’s a different story and of course they are not identical, but I’m assuming in all these hypotheticals that “same properties” means “the same in every respect.” So I would be comfortable knowing I would be instantaneously destroyed and re-created identical in all respects because I know I wouldn’t notice a difference.

That doesn’t seem to me to have any bearing on whether I would feel ok about being killed knowing my twin was alive. Of course I wouldn’t. Every me would resist being killed because I would and they are all me. If there are two copies of me in two different places, I wouldn’t say they are identical because having different experiences and perspectives (literally and figuratively) their properties differ in some respect. So then they just become two different but extremely similar people. But again I’m presuming your hypothetical means that they are identical in all respects so they must be having exactly the same experiences. So threatening to kill one either means threatening to kill both (in which case they both resist and there is no issue) or only threatening to kill one, in which case their experiences, and thus their properties, are no longer precisely identical.

Anyway, I didn’t mean to be disparaging by saying the exercise was pointless. It is an interesting way to explore identity, but if we have to make so many imposisble caveats in our hypotheticals, I’m not sure the conclusions we draw will apply especially well to any real-world question of identity. I still see identity, in any meaningful real-world sense, as a function of the properties of something. If you replaced the Mona Lisa with an exact duplicate, it doesn’t seem to me to matter if it was made by some advanced alien technology or by the original artist, it is in any sense that matters the Mona Lisa if it is indistinguishable in all respects. Hypothetically, I can see the argument you are making that the alien tech one is a “fake,” but I think in the real world the problem with fakes is that they are not indistinguishable from originals. I mean, do we value the Mona Lisa for what it is or for how it was created? Probably a bit of both but I think the former is by far the more important, and I think the latter is often irrational.

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Right—for all intents and purposes there is no difference between what we can discover as the truth and the truth itself. However we have to make a theoretical distinction between the two, because (for starters) we can always be mistaken about the facts.

For example, it could be that the fake Mona Lisa was indistinguishable by 20th century technology, but all of a sudden can be distinguished as fake by 21st century technology. Certainly we can understand that this is a possibility, and we have to always leave that sort of thing open.

Is it rational to prize originals over copies? I’m not sure. Is it irrational to prize any physical objects that are not absolutely necessary for our own survival? I wouldn’t go that far. But certainly people do in fact give importance to originals, and don’t like being duped by tricks. In this thread I personally am not so interested in the question as to whether this sort of attitude is rational or irrational. I’m simply concerned with elucidating what and when we consider something an “original” and when a “copy”. (Or, when an original has “survived” and when not).

Re: “I don’t see logically how we could have identical properties and not be identical.” ... if we are talking about literally all properties then of course you are right. But if we are talking about all intrinsic properties, then clearly we can have two objects with the same physical construction but in different physical locations. (Viz., Earth-you and Twin-Earth-you, or the different electrons, positrons, etc.)

... and what’s more, these could be literally identical in every intrinsic way, having precisely the same experiences at the same time. But in killing one you aren’t killing both, clearly. There is something indexical about existence that may go beyond simple property identity.

The point of these exercises is to get clear on the vague intermediate cases: when we consider X and Y to be the same object, and when we consider them to be different objects. Usually this sort of thing isn’t of any particular weight, but when it comes to the survival of objects and people near and dear to us, it can be disconcerting not to know precisely what to say.

I scanned over the thread as a whole, and I hope I understood you right: if I would step into the transporter, and get out on Europa, then I am killed, and an indistiguishable twin-me is living on, as if he is me, but he is fake. Still he has consciousness, and he feels like being me (has the same memories as I have even until the moment the transporter was activated), so he feels exactly like me, but I am dead.

What does that mean for me now: what makes me me? Is the only criterion the continuity? But then: Dennett discusses this continuity of consciousness, as did Buddha. Or is the continuity of my body enough? In all you other examples this physical continuity is broken: with Brennen’s wife, the Mona Lisa, and the twin me. Is that all we can say about it?

(BTW this is terrible: Kirk and Spock and Janeway are killed countless times, and nobody protests…).

I scanned over the thread as a whole, and I hope I understood you right: if I would step into the transporter, and get out on Europa, then I am killed, and an indistiguishable twin-me is living on, as if he is me, but he is fake. Still he has consciousness, and he feels like being me (has the same memories as I have even until the moment the transporter was activated), so he feels exactly like me, but I am dead.

Hello GdB:

I am taking the “Devil’s advocate” position here. I am honestly not sure what to say about these thought-experiments. But you have clearly described one of the possibilities, yes.

Here is the problem put another way: if Earth-me is destroyed in the transporter, like on Star Trek, we seem happy to say that Europa-me and Earth-me are the same person. That is, that I have survived transportation. But if Earth-me is not destroyed, it’s simply obvious that I survive on Earth, and that Europa-me is a copy, and not the real me. I’m the one who did all those things, not him. He was born in the transporter.

(Although one could say they both amount to me at least in a legal sense. If I murdered someone, both Earth-me and Europa-me would probably be prosecuted for the same crime).

And it’s odd to say that the identity of someone on Europa depends on someone else being destroyed or not destroyed back on Earth.

I don’t think that these are easy cases, and I want to get across the subteties and complexities here.

GdB - 18 October 2007 02:42 AM

What does that mean for me now: what makes me me? Is the only criterion the continuity? But then: Dennett discusses this continuity of consciousness, as did Buddha. Or is the continuity of my body enough? In all you other examples this physical continuity is broken: with Brennen’s wife, the Mona Lisa, and the twin me. Is that all we can say about it?

Well, these examples all come from Derek Parfit, and Parfit was happy with a Buddhist/Humean notion of personal identity, where personal identity was a malleable thing, depending on there being a vaguely defined stream of causal interconnectedness of mental and physical states. So I think Parfit would suggest that both of these were “me”. That is, personal identity is like identity of a stream. Streams can split and merge. So too can people, if we run the right sort of science-fiction examples. Of course, if the “me” splits, each person would have its own solitary experiences, just as if a stream splits, each half of it is a separate stream. But these would be two streams with the same source, or two “mes” with the same past ...

I’m probably not doing justice to Parfit here, though, it’s been quite a long time since I read his book.